Two active mutations (A 781 G and A 1575 G) in growth hormone (GH) gene, and their associations with litter size (LS), were investigated in both a high prolificacy (Matou, n = 182) and a low prolificacy breed (Boer, n = 352) by using the PCR-RFLP method. Superovulation experiments were designed in 57 dams, in order to evaluate the effect of different genotypes of the GH gene on superovulation response. Two genotypes (AA and AB, CC and CD) in each mutation were detected in these two goat breeds. Neither BB nor DD homozygous genotypes were observed. The genotypic frequencies of AB and CC were significantly higher than those of AA and CD. In the third parity, Matou dams with AB or CC genotypes had significantly larger litter sizes than those with AA and CD (p < 0.05). On combining the two loci, both Matou and Boer dams with ABCD genotype had the largest litter sizes when compared to the other genotypes (p < 0.05). When undergoing like superovulation treatments, a significantly higher number of corpora lutea and ova, with a lower incidence of ovarian cysts, were harvested in the AB and CC genotypes than in AA and CD. These results show that the two loci of GH gene are highly associated with abundant prolificacy and superovulation response in goat breeds.

Polymorphisms of myostatin (MSTN) gene were investigated as a candidate marker for goat growth in 687 individuals by gene sequencing and polymerase chain reaction restriction fragment length polymorphism methods. Three potential genotypes (AA, AB and BB) of 5 bp indel (1,256 TTTTA/-) in 5'UTR were detected in four breeds. The polymorphism (CC, CD and DD) of substitution (1,388 T/A) in exon 1 was only segregating in Boer. Genotype AB resulted in significant increases in body weights at birth (BW0), 90 (BW90) and 300 (BW300) days of age, and birth body length compared to BB (P < 0.05). Whilst genotype CD contributed to heavier BW0 and BW90, and larger birth body height (BH) compared to CC (P < 0.05). Individuals either with AB or CD genotype also had greater values in other body sizes, although no significant differences appeared (P > 0.05). When in combination, the combined genotype ABCD displayed positive impacts on better growth traits in BW0, BW90, BW300, BH and BCG (P < 0.05). These results indicate that these markers in myostatin (MSTN) are associated with Boer growth and may be useful for marker assisted selection.

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The aim of the current study was to estimate reproductive parameters of Matou goat to evaluate a meat breed. Data on 2,560 kids from 1,197 kidding records of 638 does and on puberty of 546 females kids were collected from farmer household herds of Matou goats in six counties of Shiye city under Hubei Province in China. Statistical analyses on puberty, estrus, gestation length (GL), litter size (LS) and survival rate (SR) of kids at puberty were performed with software Genstat 5 (Release 3.1) by using descriptive statistics and regression models. The results showed that age at puberty of female kids was 108.4+/-19.1 days while estrus duration and cycle averaged 58.6+/-15.9 hours and 19.7+/-1.5 days respectively. Gestation length (GL) and litter size (LS) averaged 150+/-7.4 days and 2.14+/-0.9 respectively with 90.8% of survival rate (SR) of kids. GL was unassociated with parity, but delayed as LS increased. SR of kids at birth differed remarkably among parity 1 to 5, decreased significantly at parity 6 to 7, and then increased at 8th parity. In Matou goat over all twinning and triplet percentage was 45.4 percent and 16.3 percent whereas percentage of single birth was 27.4 percent. As twins and triplets birth rate is considerably higher in Matou goat so, this breed can be recommended to other parts of China and the world having similar climatic conditions.

________________________________________________________________________________ AbstractThe polymorphism in the gonadotropin-releasing hormone receptor (GnRHR) gene was detected by PCR single-strand conformational (PCR-SSCP) and DNA sequencing methods in 224 Boer goats. Two single nucleotide polymorphisms (SNPs), G891T and G757A, were found in the exon I of the goat GnRHR gene and their associations with litter size in Boer goats were evaluated. Association analysis showed that G891T and G757A had significant effects on litter size. In locus G891T, individuals with GT genotype had significantly larger litter sizes compared to GG genotype in the first and third parity. In locus G757A, ewes with GG genotype had significantly higher litter sizes than those of GA in the fourth parity. The present study primarily revealed an association between allele T at 891 locus of the GnRHR gene and high litter size in the first and third parity in Boer goats. These results provide evidence that the GnRHR gene may be significantly correlated with a high prolificacy in goats.